Catalyst for reducing nitrogen oxides in gas mixt. with ammonia - contg. oxides of titanium, tungsten, molybdenum, vanadium and opt. tin

摘要

Catalyst for reducing nitrogen oxides in exhaust gases to nitrogen by contacting the exhaustion gases with gaseous ammonia, contg. a mixt. of oxides of Ti, W and/or Mo, V and opt. Sn is improved in that it contains (in atom %) Ti =50% (pref. =70%), W and/or Mo =50% (pref. =30%), V =1%, and Sn 0-10% (pref. =1%). The catalyst compsn. pref. contains 60 wt.% or more of a solid carrier. Purification of exhaust gases from internal combustion engines, combustion furnaces, industrial plants producing or employing HNO3 or nitrates, etc., is improved by selective catalytic reduction of even small amts. of NO and NO2 to N2 with NH3 without side-reactions with other components of exhaust gases such as O2, CO2, CO, water vapour or sulphur oxides. The selective action of the catalyst can be ascribed to the use of a small amt. of V in a narrow concn. range. The reaction proceeds in a wide temp. range (150-650 degrees C, pref. 150-550 degrees V). The catalyst has high activity and long service life.